// ---------- begin enumerate prime ----------
fn enumerate_prime<F>(n: usize, mut f: F)
where
    F: FnMut(usize),
{
    assert!(1 <= n && n <= 5 * 10usize.pow(8));
    let batch = (n as f64).sqrt().ceil() as usize;
    let mut is_prime = vec![true; batch + 1];
    for i in (2..).take_while(|p| p * p <= batch) {
        if is_prime[i] {
            let mut j = i * i;
            while let Some(p) = is_prime.get_mut(j) {
                *p = false;
                j += i;
            }
        }
    }
    let mut prime = vec![];
    for (i, p) in is_prime.iter().enumerate().skip(2) {
        if *p && i <= n {
            f(i);
            prime.push(i);
        }
    }
    let mut l = batch + 1;
    while l <= n {
        let r = std::cmp::min(l + batch, n + 1);
        is_prime.clear();
        is_prime.resize(r - l, true);
        for &p in prime.iter() {
            let mut j = (l + p - 1) / p * p - l;
            while let Some(is_prime) = is_prime.get_mut(j) {
                *is_prime = false;
                j += p;
            }
        }
        for (i, _) in is_prime.iter().enumerate().filter(|p| *p.1) {
            f(i + l);
        }
        l += batch;
    }
}
// ---------- end enumerate prime ----------
// floor(a ^ (1 / k))
fn kth_root(a: u64, k: u64) -> u64 {
    assert!(k > 0);
    if a == 0 {
        return 0;
    }
    if k >= 64 {
        return 1;
    }
    if k == 1 {
        return a;
    }
    let valid = |x: u64| -> bool {
        let mut t = x;
        for _ in 1..k {
            let (val, ok) = t.overflowing_mul(x);
            if !(!ok && val <= a) {
                return false;
            }
            t = val;
        }
        true
    };
    let mut ok = 1;
    let mut ng = 2;
    while valid(ng) {
        ok = ng;
        ng *= 2;
    }
    while ng - ok > 1 {
        let mid = ok + (ng - ok) / 2;
        if valid(mid) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    ok
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------

fn run() {
    input!(l: usize, r: usize);
    let mut factor = vec![vec![]; r - l + 1];
    enumerate_prime(1000000, |p| {
        let mut x = (l + p - 1) / p * p - l;
        while x < factor.len() {
            factor[x].push(p);
            x += p;
        }
    });
    let mut ans = 0;
    for (i, f) in factor.iter().enumerate() {
        let mut n = i + l;
        if n == 1 {
            ans += 1;
            continue;
        }
        let mut add = true;
        for &p in f.iter() {
            add &= n % (p * p) != 0;
            while n % p == 0 {
                n /= p;
            }
        }
        if n > 1 {
            let r = kth_root(n as u64, 2) as usize;
            add &= r * r != n;
        }
        if add {
            ans += 1;
        }
    }
    println!("{}", ans);
}

fn main() {
    run();
}